The invention relates to an apparatus for adapting the fuel quantity supplied by a fuel injection system to prevailing air temperatures. The fuel injection system supplies control information on the basis of engine rpm and air flow rate in the form of injection valve opening pulses whose duration determines the fuel quantity supplied to the engine.
It is a well known fact that the density of the air increases with decreasing temperature and this fact results in a greater air quantity admitted to the combustion chambers of the engine. Since, normally, the fuel-air ratio of the engine is attempted to be held constant, for example corresponding to the stoichiometric ratio or some other predetermined ratio, a correction is required if the fuel injection system cannot itself make the required adjustments for a changing air temperature.
In order to maintain a desired fuel-air ratio when the air temperature drops or, in the most general case, to make any arbitrary correction, a special correction is required which changes the fuel injection duration, and in the normal case, lengthens it.